A protocol for swapping one crypto asset for another on blockchains, both Layer 1 chains such as Ethereum and BNB Chain, as well as Layer 2 chains such as Polygon and Optimism. Launched in 2017 by 0x Labs, the 0x programming interface (API) adds exchange functionality to a decentralized exchange (DeX), crypto wallet or marketplace. 0x's smart order routing can split up a transaction across multiple exchanges to obtain the best rate (lowest slippage). The 0x website touts the protocol as "the liquidity endpoint for DeFi on Ethereum, etc." The native 0x token is ZRX. See
DeFi,
Matcha and
crypto glossary.